Spontaneous cold agglutination phenomenon associated with auto-anti-“N”-like antibody in a healthy blood donor

Abstract

Background: The low titer cold autoagglutinins (CAs) are found in every individual; the high-titer CAs are associated with certain infections, malignancies, or autoimmune disorders. Usually, they have specificities as anti-I; occasionally, they occur as anti-i or anti-Pr. However, CAs found that as spontaneous cold autoagglutinations (SpCAs) among the healthy blood donors are predominantly anti-i or anti-Pr besides being anti-I for their specificities. Aim: The present study is aimed to ascertain the specificity of autoantibody associated with SpCA. Study Design: The antibody in the donor's plasma and the eluate augmented from his red blood cells (RBCs) was studied. Specificity was determined using commercial and in-house RBCs panel. Standard serological methods were used. Results: A 49-year-old male volunteer donor grouped as B, RhD-negative, and M+N+ and showed a positive test for antibody screening. Direct antiglobulin test was negative though the autocontrol test was strongly positive at 4°C. The antibody eluted from the donor's RBCs showed anti-“N”-like specificity when it reacted with the trypsin-treated RBCs but not with the papain-treated RBCs. Its specificity as anti-“N” was ascertained by the failure of its reactivity with the RBCs from the M+N-S-s-U-phenotype that lacks the “N” antigen. Conclusion: SpCA phenomenon observed in this case differs from the reported cases for its specificity as anti-“N”-like.

Keywords

• Spontaneous cold agglutination phenomenon
• anti-“N”-like auto-antibody
• healthy donor